1. Field of the Invention
This invention relates to an invalid walker including means for locking at least one of the side frames in a hyperextended position.
2. Description of the Prior Art
Folding and non-folding invalid walkers are well known to those of ordinary skill in the art. An example of a typical rigid non-folding walker can be found in U.S. Design Pat. No. 234,165. An example of a prior art folding walker may be found in the disclosure of U.S. Pat. No. 3,783,886 invented by the inventor of the apparatus disclosed herein. The present inventor is also the co-inventor along with Donald W. Edwards of a "Foldable Swingable Walker" disclosed in U.S. Pat. No. 3,442,276. Other possibly relevant prior art devices are disclosed from the following U.S. Pat. Nos. 935,885; 2,397,382; 2,667,914; 2,960,148; 3,442,276; 3,658,079; 3,688,789; 3,783,886; 3,833,012 and 3,851,846.
On Nov. 23, 1976, U.S. Pat. No. 3,993,008 was issued to the present inventor, Morton I. Thomas, for a "Folding Walker". In general the device was well received by the trade. It is similar to the present invention in the limited respect that a pair of U-shaped side frames are connected together by a rotatable cross brace and the device may be locked in a normal open position by a pair of telescoping members connecting the U-shaped side frames to the cross brace member.
It was eventually discovered that the walker such as described in U.S. Pat. No. 3,993,088 was being extended beyond its normal open position for use in a variety of special circumstances. Investigation indicated that there is a need for a dependable safe invalid walker that can be converted either unilaterally or bi-laterally into a hyperextended walker. There is known to be a need for a dependable hyperextendible walker under the following conditions. Firstly, patients are frequently put in full body casts, sometimes known as body spicas, wherein the leg is positioned at an angle of approximately 45.degree. with respect to the rest of the body. Under those circumstances a normal walker interferes with the location of the leg. Secondly, patients who have experienced a full hip replacement will frequently have their legs set out at an angle as much as 45.degree. while the joint is allowed to mend. Thirdly, children who have what is known as Legg-Perthes disease are often placed in casts which extend both legs at an angle of 45.degree.. Fourthly, it is often difficult for a person to get out of a chair into a normally opened walker because the rear legs of the normally opened walker butt up against the front of the chair. A hyperextended walker would be easier to get into because it is possible to bring the front cross brace and the side grips closer to the individual trying to stand up.
Insofar as is known, there are no specifically bimodal hyperextendible invalid walkers available to the general public. It is possible to mis-use the walker disclosed in U.S. Pat. No. 3,993,088 in the hyperextended position. However, that walker when used in the hyperextended position will not remain in that position. Additionally, when only one side frame is forced into a hyperextended position, the rear foot of that side frame will generally not lie in the same plane as the other three feet of the walker. It was in the context of the foregoing prior art that the present invention arose.